I've used this stencil set extensively now. Slight learning curve on pattern overlap and placement, but with each successive gun I've painted, I've gotten better at it. First and foremost, even if buying the rifle kit for a small rifle, it wont be enough, at least not for proper flecktarn pattern. So, either buy two kits, or use an exact-o knife on the boarders and unused sections of the leftover stencil material to generate more coverage. That and study the actual pattern and use what you see for the actual stencil layout. I ignored the numbering on the sheets of stencils and went by eye next to flecktarn BDU's.
Specifically with respect to proper flecktarn, there is a LOT of overlap/coverage with your first 4 colors and if you don't do it right, your fifth and final color (light green for traditional or sand for tropentarn/arid flecktarn) will end up compromising %40+ of the final finish and darker color overlap wont look right, which makes the paint job not look that great next to the actual camo. If I could post picture here of the first AK I did vs the third gun I did I would for photographic representation. Just keep hard the lines and corners from your "custom" cut additionals on the overlap of currently placed stencils. And study the actual pattern for overlap and placement styles.
I also opted to just rattlecan. Without going into specifics, only cerakote is proper permanent and duracoat is more oil resistant but wears just like rattle can so the added baking and cooling process and cost was not worth it in my books. However, because I didn't bake the stencils, I reused them to paint 8 mags for each gun twice over (16 mags) as the adhesive remained after removal from the painted gun. So, three rounds of painting prior to disposal is worth the price in my books. Be sure to properly clean and then de-oil the surfaces prior to stencil placement and then only used latex gloves to handle the stencils/gun though to unsure proper paint adhesion and prevent premature breakdown of the stencil adhesive.
Below are links (if this will work) comparing the first and third time I did the patterns. Traditional flecktarn (green) was done with only the stencils provided while the 5 color tropentarn (tan) was done by creating my own additional to maximize coverage and overlap. The green had too much light green leftover on the final coat and didn't maximize overlap and thus doesn't match as well with the actual camo. The results speak for themselves on the tropentarn.